2018-04-14 12:42 GMT+02:00 Punit Agrawal <punitagra...@gmail.com>:
> At this point, I suspect it's a compiler issue. I've created a
> reproducer (attached) that highlights the problem and behaves
> differently on arm64 and x86.
>
> Note: I am not at all familiar with Pascal. Input from somebody more
> familiar with the language ecosystem will be greatly appreciated.
>
Great job!
Note that in your testcase, the minimized "TRectangle.ScaleAround0"
does not set Result.Width, Result.Left in some cases. And, since this
is a record, the uninitialized fields are undefined (may contain
memory garbage).
It should not matter for the result (from what I see, the
TRectangle.Width is always guaranteed to be 0 when calling this). But
maybe writing something like
"""
if Width <= 0 then
begin
Result.Width := Width;
Result.Left := Left;
end else
Writeln('This should never happen');
"""
would make this clearer?
The testcase definitely makes sense to me, and if you get different
results on different CPUs -- then indeed we have nicely reproducible
FPC bug.
(P.S. I'm the castle-game-engine upstream author.)
Regards,
Michalis
